Surface characterization by energy distribution measurements of secondary electrons and of ion‐induced electrons

Abstract

Instruments for surface microanalysis (e.g. scanning electron or ion microprobes, emission electron or ion microscopes) use the current of emitted secondary electrons or of emitted ion-induced electrons for imaging of the analysed surface. These currents, integrating over all energies of the emitted low energy electrons, are, however, not well suited to surface analytical purposes. On the contrary, the energy distribution of these electrons is extremely surface-sensitive with respect to shape, size, width, most probable energy, and cut-off energy. The energy distribution measurements were performed with a cylindrical mirror analyser and converted into N(E), if necessary. Presented are energy spectra of electrons released by electrons and argon ions of some contaminated and sputter cleaned metals, the change of the secondary electron energy distribution from oxidized aluminium to clean aluminium, and the change of the cut-off energy due to work function change of oxidized aluminium, and of a silver layer on a platinum sample. The energy distribution of the secondary electrons often shows detailed structures, probably due to low-energy Auger electrons, and is broader than the energy distribution of ion-induced electrons of the same object point.

Dopant enhanced neutralization of low-energy Li+scattered from Si(111)

“…Saturation of the work function occurs at about 1200 L, although data was collected beyond that. Changes in the surface work function with hydrogen exposure are determined from the low energy cut-off in secondary electron spectra collected with an electrostatic analyzer (Comstock) while the sample is bombarded by 200 eV electrons [23].…”

Surface restructuring in sputter-damaged Bi2Sr2CaCu2OGann1, Wen2, Xu3 et al. 2011Phys. Rev. B

“…Exposure to the alkali ion beam was limited to ensure less than 1% dosage to any spot on the specimen. The shift of the surface work function was determined by bombarding the sample with 100 eV electrons and measuring the low-energy cutoff of the secondary electron spectra with a Comstock AC-901 electrostatic analyzer, giving work function shifts to within an accuracy of 0.04 eV [15].…”